At a preview of one of Twentieth Century Fox's biggest movies of the year, Alien: Covenant star Katherine Waterston teased details of her hotly anticipated film, which she confirms will see her taking over from original Alien star Sigourney Weaver in battling extraterrestrials.

Speaking after a press screening in Los Angeles of a nail-biting scene in which the aliens first appear, she says she was terrified when she first saw the footage despite appearing in it herself.

"It freaks me out. I can't handle scary movies at all. You don't think about having to watch it," says the 36-year-old actress, who starred in the recent Harry Potter spin-off, Fantastic Beasts And Where To Find Them (2016).

In the upcoming film, she, Michael Fassbender, James Franco and Billy Crudup play crew members on the Covenant, a ship sent to colonise a remote planet.

It is a follow-up to 2012's Prometheus, which was the first prequel to the original Alien series of horror/ science-fiction movies from 1979 to 1997.

Waterston, daughter of Law & Order star Sam Waterston, also offers a glimpse at how legendary director Ridley Scott, who made the iconic films Blade Runner (1982), Thelma & Louise (1991) and Gladiator (2000), works - he is remarkably laissez-faire when it comes to his actors.

During their initial meeting, she recalls, he had said: "I like to shoot two takes of each scene and get on with the day, and come in on time and under budget, and take the cast out to dinner at night. Does that sound good to you? I don't want to get in your way - you'll read the script, you'll know what to do."

The actress adds: "And that's really what it was like - he left us all in our corners to work out what we wanted to do and we'd show it to him.

"If it was terrible, he'd say, 'That was f***ing terrible' and we'd do it better. And then we'd go to dinner."

For her, this approach was the perfect antidote to the darkness of the storyline.

"Actually, making something this dark and twisted, it was really lovely to do it with someone who's so enthusiastic about what he does and also knows how to drink a martini and have an oyster at the end of the day."

Scott told Waterston that what motivated him with the Alien movies is that he got "a sick pleasure from sitting in the audience and listening to people scream".

"And he's trying to achieve that here," she says.

The aliens in this instalment - dubbed "neomorphs" - will look different from the ones in the other films, but no less horrifying.

She and the other actors were surrounded by alien images and puppets so they would know exactly how the creatures looked.

"We saw everything ahead of shooting and we did our first read-through in a room where we were surrounded on all sides by disturbing images of the aliens and what they can do to a person. So we were all kind of green at that first reading.

"Then we got to work with a lot of puppets and stuff."

Asked if fan speculation that her character Daniels - the crew's terraforming expert - will take over the mantle of Ripley, the alien-fighting heroine played by Weaver in the earlier movies, she says: "I see that parallel for sure."

But she clarifies that Daniels' bowl haircut, which fans who saw the trailer instantly likened to Ripley's 1980s hairdo, is not a nod to the original films.

In fact, the coiff was inspired by Ezra Miller, Waterston's co-star in Fantastic Beasts And Where To Find Them.

"I had a bob for Fantastic Beasts and I was still shooting that when I got this job. And even before I got this job, I was really drawn to Ezra's haircut in that film, which is sort of a miniature bowl cut.

"When I got (this job), I saw a wig with Ezra's hairdo one night and said, 'Can I just try that on for a second?', and took a bunch of pictures and convinced Ridley to let me do it for the film.

"So I basically just totally ripped off this Fantastic Beasts hairdo from Ezra, who also put me on tape for this film," she says, referring to the video-taped audition she submitted for this role. "So I feel like I really should give him half my pay cheque."

•Alien: Covenant opens in Singapore on May 18.